The present invention relates generally to a system and method for universal ignitor control, and more particularly to an ignitor distinguishing control system and method therefor.
Most gas furnaces manufactured today include some type of electronic ignition system and, in particular, hot surface ignitors which generate temperatures of about 2,500xc2x0 F. The system typically includes an ignitor, a gas valve, and a microcomputer and related circuitry. The microcomputer and related circuitry control energizing of the ignitor to a desired ignition temperature. The ignitor, when activated, ignites gas flow passing through the gas valve to the main burner of the furnace without the use of a pilot light. These electric ignition systems increase the efficiency of the furnace, thereby increasing the efficiency of the HVAC system to which they are connected.
Several different types of ignitors exist. The most common types include silicon nitride ignitors, silicon carbide ignitors and mini silicon carbide ignitors. Each type of ignitor behaves differently during the ignitor in-rush and steady states. As a result, each type of ignitor requires a different ignitor control system for controlling operation of the ignitor and ensuring the proper and optimum operation of the furnace.
Currently, there are no means for distinguishing the type of ignitor installed in a furnace. As a result, a different type of ignitor controller is needed for each type of ignitor. Consequently, existing ignitor systems are severely limited in their ability to be used over a variety of ignitor type configurations. Moreover, when an ignitor needs to be replaced, it must be replaced with the same type of ignitor so that the ignitor control system is compatible therewith. Unfortunately, since furnaces are typically used over a long period of time (i.e. 10-20 years), certain ignitor types may no longer be available. Moreover, a new and improved ignitor may have since been developed which is more desirable. Under such circumstances, both the ignitor and the ignitor control system must be replaced.
Accordingly, there is a need for an ignitor distinguishing control system and method whereby one ignitor controller type can be used to control any type of ignitor.
An ignitor distinguishing control system for distinguishing the type of ignitor within a gas appliance in which the ignitor powered by a power source having a power source voltage, v, connected thereto and an ignitor current having a magnitude is disclosed. The system comprises an ignitor distinguishing circuit in communication with the ignitor and having a signal representative of the ignitor current through the ignitor output therefrom, and a controller in communication with the ignitor distinguishing circuit and adapted to determine the type of the ignitor based on the signal received from the ignitor distinguishing circuit. The igniter operates between an in-rush state having a beginning and an end and a steady state. The controller comprises storage for storing a plurality of control programs for controlling a plurality of corresponding ignitor types and an execution mechanism for executing the control programs corresponding to the type of ignitor determined by the controller. The plurality of control programs comprise a silicon carbide control program, a silicon nitride control programs, and a mini-silicon carbide control programs, and the plurality of corresponding ignitor types comprise a silicon carbide ignitor, a silicon nitride ignitor, and a mini-silicon carbide ignitor, respectively. The controller further comprises a comparator adapted to compare the magnitude of the igniter current of the signal at the beginning of the in-rush state to the magnitude of the ignitor current of the signal at the end of the in-rush state, and the execution mechanism comprises means for executing the silicon carbide ignitor control program when the igniter current compared by the comparator increases between the beginning and the end of the in-rush state. The controller storage also stores an ignitor current value during steady state for each of the plurality of ignitor types and for a plurality of different power source voltages, vp, and the comparator is further adapted to compare the magnitude of the ignitor current of the signal during the steady state with the ignitor current value stored within the controller storage for the power source voltage, vp, equal to the power source voltage, v, of the ignitor distinguishing control system. The execution mechanism executes the control program for the ignitor type having the ignitor current value equal to the magnitude of the ignitor current. The controller further comprises an error message generator for generating an error message to an operator of the appliance if no ignitor type is determined thereby.
A method of distinguishing the type of ignitor within a gas appliance is also disclosed. The method comprises receiving a signal from an ignitor distinguishing circuit connected to the ignitor, and determining the type of ignitor based on the signal received from the ignitor distinguishing circuit. The method may further comprise storing a plurality of control programs for controlling a plurality of corresponding ignitor types and executing the control programs corresponding to the type of ignitor determined. The plurality of control programs comprise a silicon carbide control programs, a silicon nitride control programs, and a mini-silicon carbide control programs, the plurality of corresponding ignitor types comprise a silicon carbide ignitor, a silicon nitride ignitor, and a mini-silicon carbide ignitor, respectively, and the ignitor operates between an in-rush state having a beginning and an end and a steady slate. The method further comprises comparing the magnitude of the ignitor current at the beginning of the in-rush state to the magnitude of the ignitor current at the end of the in-rush state and executing the silicon carbide ignitor control program when the magnitude of the ignitor current increases between the beginning and the end of the in-rush state. The method further comprises storing an ignitor current value during steady state for each of the plurality of ignitor types and for a plurality of power source voltages, vp, comparing the magnitude of the ignitor current of the signal during the steady state with the ignitor current value stored within the controller storage for the power source voltage, vp, equal to the power source voltage, v, of the ignitor, and executing the control program for the ignitor type having the ignitor current value equal to the magnitude of the ignitor current. The method may further comprise generating an error message to an operator of the appliance if no ignitor type is determined.
While the principal advantages and features of the present invention have been explained above, a more complete understanding of the invention may be attained by referring to the description of the preferred embodiments.